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620 XL vs 420-BG 5 of 19 identical Swap Change panels

Silfab SIL-620 XL vs Silfab SIL-420-BG

Silfab
SIL-620 XL
620 Wp 22.20 % N-type Bifacial
Open panel page Datasheet PDF
VS
Silfab
SIL-420-BG
420 Wp 21.90 % PERC
Open panel page Datasheet PDF
The verdict

620 XL leads on the differences that matter

The largest is temperature coefficient: 0.087 %/°C better in heat. 5 of 19 comparable parameters are identical.

See all 14 differences
How alike are they
5 of 19 comparable
parameters are identical
identical differs
01

What actually differs

14 of 19 parameters
Parameter 620 XL 420-BG Difference
Temperature coefficient -0.290 %/°C -0.377 %/°C 0.087 %/°C better in heat
Rated power 620 Wp 420 Wp 200 W more power
Weight 29.5 kg 20.8 kg 8.7 kg lighter
Open-circuit voltage 57.21 V 46.36 V 10.85 V apart
Short-circuit current 13.55 A 11.40 A 2.15 A apart
Module area 2.793 m² 1.918 m² 0.875 m² apart
Module efficiency 22.20 % 21.90 % 0.30 pp more efficient
Cell technology N-type PERC N-type vs PERC
Power density 222.0 Wp/m² 219.0 Wp/m² 3.0 Wp/m² higher
Voltage at max power 48.16 V 38.51 V 9.65 V apart
Cell count 156 66 90 cells apart
Current at max power 12.87 A 10.91 A 1.96 A apart
Bifacial Yes No Yes vs No
Dimensions 2465x1133x35 mm 1864x1029x35 mm 2465x1133x35 mm vs 1864x1029x35 mm
02

What it means on a roof

Thirty years of production
Each panel's own declared degradation curve, at 1,200 kWh/kWp a year
620 XL
20,903 kWh
420-BG
14,160 kWh
Lifetime gap
6,743 kWh
Output when it is hot
Rated power carried across the range a module actually sees
Scenario 620 XL 420-BG
Standard test conditions 25 °C 100.0% of rated power 620 W 420 W
Cool, bright day 40 °C 94.3% of rated power 593 W 396 W
Typical summer roof 55 °C 88.7% of rated power 566 W 372 W
Hot roof 70 °C 83.0% of rated power 539 W 349 W
03

Full specification

Parameter 620 XL 420-BG Difference
Power and efficiency
Rated power 620 Wp 420 Wp +200 W for 620 XL
Module efficiency 22.20 % 21.90 % +0.30 pp for 620 XL
Power density 222.0 Wp/m² 219.0 Wp/m² +3.0 Wp/m² for 620 XL
Open-circuit voltage 57.21 V 46.36 V 10.85 V apart
Voltage at max power 48.16 V 38.51 V 9.65 V apart
Short-circuit current 13.55 A 11.40 A 2.15 A apart
Current at max power 12.87 A 10.91 A 1.96 A apart
Temperature
Temperature coefficient -0.290 %/°C -0.377 %/°C +0.087 %/°C for 620 XL
Mechanical
Dimensions 2465x1133x35 mm 1864x1029x35 mm 2465x1133x35 mm vs 1864x1029x35 mm
Module area 2.793 m² 1.918 m² 0.875 m² apart
Weight 29.5 kg 20.8 kg -8.7 kg for 420-BG
Weight per kWp 47.6 kg/kWp 49.5 kg/kWp Effectively the same
Warranty and degradation
Product warranty 25 yrs 25 yrs Same
Performance warranty 30 yrs 30 yrs Same
Annual degradation 0.30 %/yr 0.30 %/yr Same
Technology
Cell technology N-type PERC N-type vs PERC
Cell type Monocrystalline Monocrystalline Same
Cell count 156 66 90 cells apart
Bifacial Yes No Yes vs No
04

Against the whole database

14,129 panels
Efficiency
#5,881 vs #6,847
620 XL leads by 966 places
Power density
#5,913 vs #6,850
620 XL leads by 937 places
Heat behaviour
#2,220 vs #13,470
620 XL leads by 11,250 places
Weight
#1,762 vs #3,065
620 XL leads by 1,303 places
Warranty
#21 vs #21
Tied - the same position in the database
Overall
#1,420 vs #8,049
620 XL leads by 6,629 places
05

More useful comparisons

Open the full database
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Silfab SIL-620 XL vs Silfab SIL-640 XL
3 differences, the largest is module efficiency
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Silfab SIL-620 XL vs Silfab SIL-630 XL
3 differences, the largest is module efficiency
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Silfab SIL-420-BG vs Silfab SIL-430 BG+
9 differences, the largest is module efficiency
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Silfab SIL-420-BG vs Silfab SIL-410-BG
3 differences, the largest is module efficiency
Same series, other bin
Silfab
Silfab SIL-420-BG vs Silfab SIL-380 BK
10 differences, the largest is rated power
Same series, other bin
Silfab
Silfab SIL-420-BG vs Silfab SIL-370 BK
10 differences, the largest is module efficiency
06

Written summary

07

Questions about this pairing

Which panel is better: Silfab SIL-620 XL or Silfab SIL-420-BG?
According to our database: Silfab SIL-620 XL has higher module efficiency (22.20% vs 21.90%); Silfab SIL-620 XL tolerates heat better (temp coeff -0.290%/°C vs -0.377%/°C). See the full spec comparison and 30-year energy simulation above for a complete picture.
What is the efficiency of Silfab SIL-620 XL and Silfab SIL-420-BG?
Silfab SIL-620 XL has a module efficiency of 22.20%, while Silfab SIL-420-BG is 21.90%. Higher efficiency means more electricity from the same roof area - useful when space is limited.
What cell technology does Silfab SIL-620 XL use vs Silfab SIL-420-BG?
Silfab SIL-620 XL uses N-type cells; Silfab SIL-420-BG uses PERC. Modern n-type technologies (TOPCon, HJT, BC) typically deliver higher efficiency and lower degradation compared to older PERC (p-type) cells.
What is the warranty on Silfab SIL-620 XL and Silfab SIL-420-BG?
Silfab SIL-620 XL has a 30 years power warranty; Silfab SIL-420-BG has a 30 years power warranty. The power warranty guarantees a minimum percentage of rated output at the end of the warranty period (typically 80-87%). Product (materials) warranties are usually shorter.
Are Silfab SIL-620 XL and Silfab SIL-420-BG bifacial panels?
Silfab SIL-620 XL is bifacial (captures light from both faces); Silfab SIL-420-BG is monofacial. Bifacial panels work best on ground mounts or raised structures with a light-coloured surface underneath.

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Every figure here is from the manufacturers' own datasheets - a dash means the value is not published, never an estimate. The thirty-year projection and the temperature scenarios are calculations from those figures, and each states its assumption above.